Process of preparing alkali cellulose



Patented Nov. 10, 1931 UNITED. srrs HARRY I. BASSETT, OF CYNTHIANA, KENTUCKY PROCESS OF PREPARING ALKALI GELLULOSE No Drawing. Application filed April 13, 1928, Serial No. 269,877. Renewed April 2, 1931. I

This invention relates to a process of preparing alkali cellulose.

The principal object of this invention is to treat cellulose material to form alkali cellulose in a simple and advantageous manner and with the production ofa product superior to that produced by the methods of forming alkali cellulose heretofore employed.

An important object of this invention is to provide a process for producing alkali cellulose from cellulose fibers such as cotton linters or Wood pulp in an efficient and relatively inexpensive manner and with the expenditure of a less amount or labor than has been involved in the processes heretofore employed for the production of alkali cellulose.

A further object of this invention is to provide a process of producing alkali cellulose from cellulose fibers wherein a more efficient chemical and mechanical control of the process is provided than in the processes of producing alkali cellulose heretofore employed.

In the preferred practice of my process cellulose material such for example, as cotton linters or wood pulp is introduced into a suitable digester in loose form, the cellulose material preferably being agitated, as by means of a stirrer of conventional construc tion. The cellulose material is then treated with a caustic solution of mercerizing strength, any suitable caustic solution of mercerizing strength being employed. For example, an aqueous solution of caustic soda or caustic potash containing from 16 to 24: per cent, but preferably 18 per cent, by weight of caustic may advantageously be employed. The amount of caustic solution used to treat the cellulose material will vary according to the grade and source of the stock being treated but I prefer to employ an amount of caustic equal to that commonly employed in present processes for merceriz ing cellulose materials. The cellulose material is treated with the caustic solution, preferably with agitation, for a period of from minutes to 2 hours to effect the formation of alkali cellulose. I have found that a treatment of approximately a5 minutes is ordinarily suflicient but this period of time may be varied within'the range set forth above oven formation of alkali cellulose.

as will be apparent to those skilled in the art.

After the cellulose material has been treated in the manner described above it is then introduced into a centrifugalinachine and the excess of the caustic solution removed by centrifuging in the well known manner. The partially treated linters, pulp or other cellulose material are then aged for a period of preferably from 1 to 3 days to secure an The aged mat rial is then freed from an additional amount of the caustic solution preferably by means of a dehydrating press of the type commonly employed in the manufacture of nitro cotton. I prefer to press the material until there is approximately from 25 to per cent. of actual cellulose content present. While I prefer to press the cellulose material after the aging thereof I have found that it is possible to obtain ahigh measure of success by pressingthe material in the manner described above prior to the aging step. After the desired amount of liquid has been removed from the cellulose material the l,

pressed block of the material is removed from tne dehydrating press and is preferably shredded in any suitable manner as for example by means of a tumbler, a disintegrating drum, a Werner-Pfleiderer machine, or

other suitable device, to place the cellulose material in fiulfy form. Such material may then be treated with carbon disulfide or otherwise treated in any suitable manner according to conventional processes for making films, artificial silk, artificial horse hair or other cellulose products. If desired it will be apparent that the block of cellulose material removed from the dehydrating press need not be shreddedor otherwise treated in the manner outlined but may be employed in the practice of any desired process of producing cellulose products.

: From the foregoing it will be apparent that I have provided a simple, efficient, and economical process of preparing alkalicellulose from cellulose materials. 7 It will also be apparent that a minimum amount of labor is required forthe process and that certain steps heretofore employed in similar processes,

such asai beating step, are avoided. The

soda cellulose produced according to my process is of extremely high purity and par-- ticularly advantageous for use in the preparation of viscose solutions for use in preparing artificial silk and other cellulose products.

While I have described in detail the preferred practice of my process it will be understood that the details of procedure, the ingredients employed, and the arrangement of steps may be widely varied without departing from the spirit of the invention or the scope of the subjoined claims.

I claim:

1. The herein described process of treating cellulose material which comprises treating said material with a caustic solution of mercerizing strength for a period of from 30 minutes to 2- hours, centrifuging said material to remove the excess liquid present, aging said material for a period of from 1 to 3 days to provide a substantially even formation of alkali cellulose, and pressin said material to provide approximately from 25 to 35 per cent. actual cellulose content therein.

2. The herein described process of treating cellulose material which comprises treating such material in loose form with an aqueous solution of from approximately 16 to 24 per cent. by weight caustic alkali for a period of from 30 minutes to 2 hours, centrifuging said material to remove the excess of alkali solution therefrom, aging said material for from 1 to 3 days, pressing said material to provide approximately from 25 to 35 per cent. actual cellulose content therein, and shredding said material.

3. The herein described process which comprises treating cellulose material in loosely divided condition with a caustic solution of mercerizing strength for a period of approximately from 30 minutes to 2% hours, removing the excess of the solution from the material, aging said material to provide a substantially even formation of alkali cellulose, and expelling additional amounts of the solution from said material to provide approximately from 25 to 35 per cent. actual cellulose content therein.

l. The herein described process which comprises treating cellulose material With a caustic solution of mercerizing strength to effect the formation of alkali cellulose, removing the excess of the solution from the material, aging said material to provide a substantially even formation of alkali cellulose, and pressing the resulting material to provide approximately from 25 to 35 per cent. actual cellulose content therein.

5. The herein described process which comprises treating cellulose material in loosely divided condition with a caustic solution of mercerizing strength for a period of from 30 minutesto 2 hours, removing the excess ture. v

HARRY P. BASSETT. 

